MAXIM MAX8884YEREKE+T

19-4418; Rev 1; 1/10
700mA DC-DC Step-Down Converters
with Dual 300mA LDO in 2mm x 2mm CSP
Features
The MAX8884Y/MAX8884Z step-down converters with
dual low-dropout (LDO) linear regulators are intended to
power low-voltage microprocessors, DSPs, camera and
Wi-Fi modules, or other point of load applications in
portable devices. These ICs feature high efficiency with
small external component size. The step-down converter
output voltage is pin selectable between 1.2V and 1.8V,
and provides guaranteed output current of 700mA. The
2/4MHz hysteretic-PWM control scheme allows for tiny
external components and reduces no-load operating
current to 50µA. Two low quiescent current, low-noise
LDOs operate down to 2.7V supply voltage. Two switching frequency options are available—MAX8884Y (2MHz)
and MAX8884Z (4MHz)—allowing optimization for smallest solution size or highest efficiency. Fast switching
allows the use of small ceramic 2.2µF input and output
capacitors while maintaining low ripple voltage. The
MAX8884Y/MAX8884Z have individual enables for each
output, maximizing flexibility.
The MAX8884Y/MAX8884Z are available in a 16-bump,
2mm x 2mm CSP package (0.7mm max height).
o Step-Down Converter
Pin-Selectable Output Voltage (1.2V/1.8V)
2MHz or 4MHz Switching Frequency
Low-Output Voltage Ripple
700mA Output Drive Capability
Simple Logic ON/OFF Control
Tiny External Components
o Low-Noise LDOs
2 x 300mA LDO
Pin-Selectable Output Voltage (LDO1)
Low 26µVRMS (typ) Output Noise
High 65dB (typ) PSRR
Simple Logic ON/OFF Control
o Low 0.1µA Shutdown Current
o 2.7V to 5.5V Supply Voltage Range
o Thermal Shutdown
o Tiny, 2mm x 2mm x 0.65mm CSP Package (4x4 Grid)
Applications
Cell Phones/Smartphones
Ordering Information
PART
PIN-PACKAGE
SWITCHING
FREQUENCY
MAX8884YEREKE+T
16 CSP
2MHz
MAX8884ZEREKE+T
16 CSP
4MHz
Note: All devices are specified over the -40°C to +85°C operating temperature range.
PDA and Palmtop Computers
Portable MP3 and DVD Players
Digital Cameras, Camcorders
+Denotes a lead(Pb)-free/RoHS-compliant package.
T = Tape and reel.
PCMCIA Cards
Typical Application Circuit appears at end of data sheet.
Handheld Instruments
Pin Configuration
Typical Operating Circuit
TOP VIEW
(BUMPS ON BOTTOM)
BATT
2.7V TO 5.5V
BUCK
1.2V/1.8V
IN1A
2.2µF
IN1B
BUCK ON/OFF
MAX8884Y
BUCK_EN MAX8884Z
MAX8884Y
MAX8884Z
FB
LX
A1
A2
A3
A4
PGND
REFBP
AGND
NC1
PGND
REFBP
B1
B2
B3
B4
LDO2
BUCK_EN
LDO2_EN
LX
C1
C2
C3
C4
IN2
SEL
IN1B
IN1A
D1
D2
D3
D4
LDO1
LDO1_EN
NC2
FB
2.2µH
BUCK/LDO1 VOLTAGE
SELECTION
SEL
LDO1 ON/OFF
LDO1_EN
LDO2 ON/OFF
LDO2_EN
AGND
LDO1
BATT
2.7V TO 5.5V
IN2
2.2µF
LDO2
VLDO1
UP TO 300mA
VLDO2
UP TO 300mA
CSP
________________________________________________________________ Maxim Integrated Products
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
1
MAX8884Y/MAX8884Z
General Description
MAX8884Y/MAX8884Z
700mA DC-DC Step-Down Converters
with Dual 300mA LDO in 2mm x 2mm CSP
ABSOLUTE MAXIMUM RATINGS
IN1A, IN1B, IN2, REFBP to AGND ........................-0.3V to +6.0V
FB to PGND ...........................................................-0.3V to +6.0V
SEL, BUCK_EN to AGND...............-0.3V to (VIN1A/VIN1B + 0.3V)
LDO1, LDO2, LDO1_EN, LDO2_EN
to AGND.................................................-0.3V to (VIN2 + 0.3V)
IN2 to IN1A, IN1B ..................................................-0.3V to +0.3V
AGND to PGND .....................................................-0.3V to +0.3V
IN1A, IN1B, LX Current .....................................................1ARMS
Continuous Power Dissipation (TA = +70°C)
16-Bump CSP (derate 12.5mW/°C above +70°C) ..............1W
Operating Temperature .......................................-40°C to +85°C
Junction Temperature ......................................................+150°C
Storage Temperature Range .............................-65°C to +150°C
Bump Temperature*.........................................................+260°C
*These ICs are constructed using a unique set of packaging techniques imposing a limit on the thermal profile used during board level
solder attach and rework. This limit permits only the use of the solder profiles recommended in the industry-standard specification,
JEDEC 020A, paragraph 7.6, Table 3 for IR/VPR and Convection reflow. Preheating is required. Hand or wave soldering is not allowed.
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
ELECTRICAL CHARACTERISTICS
(VIN1A = VIN1B = VIN2 = VLDO1_EN = VLDO2_EN = VBUCK_EN = 3.6V. TA = -40°C to +85°C, typical values are at TA = +25°C, unless
otherwise noted.) (Note 1)
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
5.5
V
2.63
2.70
V
TA = +25°C
0.1
4
TA = +85°C
0.1
INPUT SUPPLY
Input Voltage
VIN1A, VIN1B, VIN2
2.7
Input Undervoltage Threshold
VIN1A, VIN1B, VIN2 rising, 180mV typical hysteresis
2.52
Shutdown Supply Current
VBUCK_EN = VLDO1_EN =
VLDO2_EN = 0
No-Load Supply Current
VBUCK_EN = 0, ILDO1 = ILDO2 = 0A
VLDO1_EN = VLDO2_EN = 0, IBUCK = 0A, no switching
µA
140
230
µA
50
80
µA
THERMAL PROTECTION
Thermal Shutdown
TA rising, 20°C typical hysteresis
+160
°C
LOGIC CONTROL
Logic Input-High Voltage
(BUCK_EN, SEL, LDO1_EN,
LDO2_EN)
2.7V VIN1A = VIN1B = VIN2 5.5V
Logic Input-Low Voltage
(BUCK_EN, SEL, LDO1_EN,
LDO2_EN)
2.7V VIN1A = VIN1B = VIN2 5.5V
Logic Input Current (BUCK_EN,
SEL, LDO1_EN, LDO2_EN)
VIL = 0 or VIH = VIN1A = 5.5V
1.3
V
0.4
TA = +25°C
0.01
TA = +85°C
0.1
1
V
µA
FB
Buck Converter Output Voltage
SEL = AGND, IBUCK = 0A
VSEL = VIN1A, IBUCK = 0A
FB Leakage Current
VIN1A = VIN1B = VIN2 = 5.5V,
VFB = 0
1.18
1.78
1.22
1.24
V
V
1.80
1.85
TA = +25°C
0.01
1
TA = +85°C
1
µA
LX
On-Resistance
2
p-channel MOSFET switch, ILX = -40mA
0.18
0.30
n-channel MOSFET rectifier, ILX = 40mA
0.15
0.25
_______________________________________________________________________________________
700mA DC-DC Step-Down Converters
with Dual 300mA LDO in 2mm x 2mm CSP
(VIN1A = VIN1B = VIN2 = VLDO1_EN = VLDO2_EN = VBUCK_EN = 3.6V. TA = -40°C to +85°C, typical values are at TA = +25°C, unless
otherwise noted.) (Note 1)
PARAMETER
LX Leakage Current
CONDITIONS
VIN1A = VIN1B = VIN2 = 5.5V,
VLX = 0
MIN
TYP
MAX
TA = +25°C
0.1
1
TA = +85°C
1
UNITS
µA
p-Channel MOSFET Peak Current
VLX = 0
Limit
0.8
1.0
1.2
A
n-Channel MOSFET Valley
Current Limit
0.6
0.8
1.0
A
n-Channel MOSFET
Zero-Crossing Threshold
MAX8884Y_
40
MAX8884Z_
60
Minimum On-Time
mA
0.07
Minimum Off-Time
µs
0.06
Power-Up Delay
From VBUCK_EN rising to VLX rising
µs
120
250
1.800
1.836
µs
LDO1, LDO2
Output Voltage VLDO1
VIN2 = 5.5V, ILDO_ = 1mA;
VIN2 = 3.4V, ILDO_ = 100mA
Output Voltage VLDO2
VIN2 = 5.5V, ILDO_ = 1mA;
VIN2 = 3.4V, ILDO_ = 100mA
SEL = AGND
1.764
SEL = IN1_
Output Current
V
2.800
2.770
2.800
2.830
450
750
200
300
mA
Current Limit
VLDO_ = 0
Dropout Voltage
ILDO_ = 100mA, TA = +25°C (VLDO_ 2.5V)
70
Line Regulation
VIN2 stepped from 3.5V to 5.5V, ILDO_ = 100mA
2.4
mV
Load Regulation
ILDO_ stepped from 50µA to 200mA
25
mV
Power-Supply Rejection
VLDO_/VIN2
10Hz to 100kHz, VLDO_ = 1.8V,
CLDO_ = 2.2µF, ILDO_ = 30mA
65
dB
Output Noise
10Hz to 100kHz, VLDO_ = 1.8V,
CLDO_ = 2.2µF, ILDO_ = 30mA
26
µVRMS
0 < ILDO_ < 10mA
0.1
Output Capacitor for Stable
Operation
310
V
mA
mV
µF
10mA < ILDO_ < 200mA
200mA < ILDO_ < 300mA
1
2.2
Shutdown Output Impedance
VLDO1_EN = VLDO2_EN = 0
100
Power-Up Delay
From VLDO_EN rising to VLDO_ output rising
150
250
µs
1.250
1.263
V
0.2
5
mV
REFBP
REFBP Output Voltage
0 IREFBP 1µA
REFBP Supply Rejection
VIN2 stepped from 2.55V to 5.5V
1.237
Note 1: All devices are 100% production tested at TA = +25°C. Limits over the operating temperature range are guaranteed by
design.
_______________________________________________________________________________________
3
MAX8884Y/MAX8884Z
ELECTRICAL CHARACTERISTICS (continued)
Typical Operating Characteristics
(VIN = VIN1A = VIN1B = VIN2 = 3.6V, VBUCK = 1.2V, VLDO1 = 1.8V, VLDO2 = 2.8V, MAX8884YEVKIT, TA = +25°C, unless otherwise noted.)
90
80
70
EFFICIENCY (%)
EFFICIENCY (%)
80
MAX8884Y, VIN = 3.2V
= 3.6V
= 4.2V
MAX8884Z, VIN = 3.2V
= 3.6V
= 4.2V
60
50
70
MAX8884Y, VIN = 3.2V
= 3.6V
= 4.2V
MAX8884Z, VIN = 3.2V
= 3.6V
= 4.2V
60
50
300
MAX8884Y/Z toc03
90
MAX8884Y/Z toc02
100
MAX8884Y/Z toc01
100
STEP-DOWN CONVERTER NO-LOAD
SUPPLY CURRENT vs. INPUT VOLTAGE
STEP-DOWN CONVERTER EFFICIENCY
vs. LOAD CURRENT, VOUT = 1.2V
VBUCK_EN = VIN
VLDO1_EN = VLDO2_EN = 0
250
SUPPLY CURRENT (µA)
STEP-DOWN CONVERTER EFFICIENCY
vs. LOAD CURRENT, VOUT = 1.8V
200
VIN FALLING
150
VIN RISING
100
40
40
50
30
30
0
MAX8884Y
MAX8884Z
1
10
100
1000
10
1
100
0
1000
1
2
3
4
5
LOAD CURRENT (mA)
LOAD CURRENT (mA)
INPUT VOLTAGE (V)
STEP-DOWN OUTPUT VOLTAGE vs. LOAD
CURRENT (VOLTAGE POSITIONING)
MAX8884Z STEP-DOWN CONVERTER
LIGHT LOAD SWITCHING WAVEFORMS
MAX8884Y STEP-DOWN CONVERTER
LIGHT LOAD SWITCHING WAVEFORMS
1.8
SEL = IN1_
1.7
VOUT
1.6
ILX
1.5
AC-COUPLED
VOUT
20mV/div
AC-COUPLED
10mV/div
100mA/div
100mA/div
ILX
0A
0A
1.4
6
MAX8884Y/Z toc06
MAX8884Y/Z toc05
MAX8884Y/Z toc04
1.9
OUTPUT VOLTAGE (V)
MAX8884Y/MAX8884Z
700mA DC-DC Step-Down Converters
with Dual 300mA LDO in 2mm x 2mm CSP
1.3
VLX
1.2
2V/div
SEL = AGND
1.1
2V/div
VLX
0V
0V
ILOAD = 50mA
1.0
1
10
100
1000
1µs/div
400ns/div
LOAD CURRENT (mA)
MAX8884Z STEP-DOWN CONVERTER
HEAVY LOAD SWITCHING WAVEFORMS
MAX8884Y STEP-DOWN CONVERTER
HEAVY LOAD SWITCHING WAVEFORMS
MAX8884Y/Z toc07
MAX8884Y/Z toc08
AC-COUPLED
10mV/div
VOUT
ILX
500mA/div
AC-COUPLED
10mV/div
VOUT
500mA/div
ILX
0A
0A
2V/div
VLX
VLX
2V/div
0V
0V
ILOAD = 500mA
ILOAD = 500mA
200ns/div
4
400ns/div
_______________________________________________________________________________________
700mA DC-DC Step-Down Converters
with Dual 300mA LDO in 2mm x 2mm CSP
MAX8884Z STEP-DOWN CONVERTER
SOFT-START WAVEFORMS
MAX8884Y STEP-DOWN CONVERTER
SOFT-START WAVEFORMS
MAX8884Y/Z toc09
VOUT
MAX8884Y/Z toc10
1V/div
VOUT
1V/div
0V
200mA/div
IIN1
0V
200mA/div
IIN1
0A
500mA/div
ILX
0A
500mA/div
ILX
0A
2V/div
VBUCK_EN
ILOAD = 500mA
0A
2V/div
VBUCK_EN
ILOAD = 500mA
0V
40µs/div
40µs/div
MAX8884Y STEP-DOWN CONVERTER
LINE TRANSIENT RESPONSE
MAX8884Z STEP-DOWN CONVERTER
LINE TRANSIENT RESPONSE
MAX8884Y/Z toc11
4V
MAX8884Y/Z toc12
4V
4V
1V/div
VIN
4V
1V/div
VIN
3.5V
3.5V
AC-COUPLED
20mV/div
VOUT
ILX
200mA/div
ILOAD = 500mA
AC-COUPLED
20mV/div
VOUT
ILX
200mA/div
ILOAD = 500mA
0A
10µs/div
10µs/div
MAX8884Z STEP-DOWN CONVERTER
LOAD TRANSIENT
MAX8884Y STEP-DOWN CONVERTER
LOAD TRANSIENT
1.8V DC OFFSET
100mV/div
VOUT
500mA/div
ILX
1.8V DC OFFSET
100mV/div
VOUT
500mA/div
ILX
0A
0A
500mA/div
IOUT
500mA
500mA
500mA/div
10mA
0A
MAX8884Y/Z toc14
MAX8884Y/Z toc13
IOUT
0V
0A
10mA
10mA
10mA
0A
20µs/div
20µs/div
_______________________________________________________________________________________
5
MAX8884Y/MAX8884Z
Typical Operating Characteristics (continued)
(VIN = VIN1A = VIN1B = VIN2 = 3.6V, VBUCK = 1.2V, VLDO1 = 1.8V, VLDO2 = 2.8V, MAX8884YEVKIT, TA = +25°C, unless otherwise noted.)
Typical Operating Characteristics (continued)
(VIN = VIN1A = VIN1B = VIN2 = 3.6V, VBUCK = 1.2V, VLDO1 = 1.8V, VLDO2 = 2.8V, MAX8884YEVKIT, TA = +25°C, unless otherwise noted.)
MAX8884Y STEP-DOWN CONVERTER
SHUTDOWN WAVEFORMS
LDO1, LDO2 INPUT SUPPLY CURRENT
vs. INPUT VOLTAGE
MAX8884Y/Z toc15
ILX
500mA/div
0A
VBUCK_EN
ILOAD = 500mA
VLDO1_EN = VLDO2_EN = VIN,
VBUCK_EN = 0
300
SUPPLY CURRENT (µA)
0V
MAX8884Y/Z toc16
350
1V/div
VOUT
250
200
150
100
50
5V/div
0V
0
0
10µs/div
1
2
3
4
5
6
INPUT VOLTAGE (V)
LDO POWER SUPPLY
RIPPLE REJECTION, VOUT = 1.8V
LDO2 DROPOUT VOLTAGE
vs. LOAD CURRENT
150
100
MAX8884Y/Z toc18
DROPOUT VOLTAGE (V)
200
80
70
RIPPLE REJECTION (dB)
MAX8884Y/Z toc17
250
60
50
40
30
20
50
10
ILDO = 30mA
0
0
0
50
100
150
200
250
300
0.01
0.1
1
10
100
LOAD CURRENT (mA)
FREQUENCY (kHz)
LDO POWER SUPPLY
RIPPLE REJECTION, VOUT = 2.8V
LDO OUTPUT VOLTAGE
NOISE WAVEFORM, VOUT_ = 1.8V
MAX8884Y/MAX8884Z
LDO1 = 1.8 AT 30mA
VIN = 3.6V
MAX8884Y/Z toc19
60
50
40
50µV/div
30
20
10
VN = 26.1µVRMS,
f = 100Hz to 100kHz, ILDO_ = 30mA
ILDO_ = 30mA
0
0.01
0.1
1
10
100
1000
400µs/div
FREQUENCY (kHz)
6
1000
MAX8884Y/Z toc20
70
RIPPLE REJECTION (dB)
MAX8884Y/MAX8884Z
700mA DC-DC Step-Down Converters
with Dual 300mA LDO in 2mm x 2mm CSP
_______________________________________________________________________________________
700mA DC-DC Step-Down Converters
with Dual 300mA LDO in 2mm x 2mm CSP
LDO OUTPUT-NOISE SPECTRAL DENSITY
vs. FREQUENCY, VLDO_ = 1.8V
1000
100
MAX884Y/Z toc22
10,000
NOISE DENSITY (nV√(Hz))
MAX884Y/Z toc21
NOISE DENSITY (nV√(Hz))
10,000
LDO OUTPUT-NOISE SPECTRAL DENSITY
vs. FREQUENCY, VLDO_ = 2.8V
1000
100
ILDO_ = 30mA
ILDO_ = 30mA
10
10
0.01
0.1
1
10
100
0.01
1000
FREQUENCY (kHz)
0.1
1
10
LDO1, LDO2 LINE TRANSIENT
1000
LDO1, LDO2 LOAD TRANSIENT RESPONSE
MAX8884Y/Z toc23
4V
100
FREQUENCY (kHz)
MAX8884Y/Z toc24
4V
VIN
ILDO2
1V/div
3.5V
50mA/div
40mA
1mA
1mA
AC-COUPLED
10mV/div
VLDO2
VLDO1
AC-COUPLED
5mV/div
VLDO2
AC-COUPLED
5mV/div
ILDO1
40mA
1mA
50mA/div
1mA
AC-COUPLED
10mV/div
VLDO1
ILDO1 = ILDO2 = 100mA
10µs/div
20µs/div
LDO1, LDO2 LOAD TRANSIENT
RESPONSE NEAR DROPOUT
LDO1, LDO2 STARTUP
AND SHUTDOWN RESPONSE
MAX8884Y/Z toc26
MAX8884Y/Z toc25
50mA/div
40mA
ILDO2
1mA
1mA
AC-COUPLED
10mV/div
VLDO2
50mA/div
40mA
ILDO1
1mA
VLDO1_EN =
VLDO2_EN
2V/div
0V
VLDO1
2V/div
0V
VLDO2
2V/div
0V
1mA
AC-COUPLED
10mV/div
VLDO1
VIN2 = VLDO2 + 200mV
20µs/div
400µs/div
_______________________________________________________________________________________
7
MAX8884Y/MAX8884Z
Typical Operating Characteristics (continued)
(VIN = VIN1A = VIN1B = VIN2 = 3.6V, VBUCK = 1.2V, VLDO1 = 1.8V, VLDO2 = 2.8V, MAX8884YEVKIT, TA = +25°C, unless otherwise noted.)
Typical Operating Characteristics (continued)
(VIN = VIN1A = VIN1B = VIN2 = 3.6V, VBUCK = 1.2V, VLDO1 = 1.8V, VLDO2 = 2.8V, MAX8884YEVKIT, TA = +25°C, unless otherwise noted.)
REFBP SOFT-START
CREFBP = 0.033µF
REFBP SOFT-START
CREFBP = 0.15µF
MAX8884Y/Z toc27
MAX8884Y/Z toc28
1V/div
VREFBP
1V/div
VREFBP
0V
0V
2V/div
VLDO1_EN
VLDO1_EN
2V/div
0V
VLDO1
1V/div
0V
1V/div
VLDO1
0V
100µs/div
MAX8884Y SWITCHING FREQUENCY
vs. OUTPUT CURRENT (VOUT = 1.8V)
MAX8884Y SWITCHING FREQUENCY
vs. OUTPUT CURRENT (VOUT = 1.2V)
2.0
1.8
VIN = 3.6V
1.6
1.4
VIN = 3V
2.2
VIN = 4.2V
2.0
1.8
1.6
VIN = 3.6V
VIN = 3V
1.4
1.2
1.2
CIN = COUT = 2.2µF, L = 2.2µH
CIN = COUT = 2.2µF, L = 2.2µH
1.0
1.0
100
300
500
700
300
100
900
500
700
900
LOAD CURRENT (mA)
MAX8884Z SWITCHING FREQUENCY
vs. OUTPUT CURRENT (VOUT = 1.8V)
MAX8884Z SWITCHING FREQUENCY
vs. OUTPUT CURRENT (VOUT = 1.2V)
4.0
3.5
VIN = 3.6V
3.0
VIN = 3V
2.5
MAX8884Y/Z toc32
4.5
5.0
SWITCHING FREQUENCY (MHz)
VIN = 4.2V
MAX8884Y/Z toc31
LOAD CURRENT (mA)
5.0
4.5
4.0
VIN = 4.2V
3.5
VIN = 3.6V
3.0
VIN = 3V
CIN = COUT = 2.2µF, L = 2.2µH
CIN = COUT = 2.2µF, L = 2.2µH
2.5
2.0
100
300
500
700
LOAD CURRENT (mA)
8
MAX8884Y/Z toc30
2.2
2.4
SWITCHING FREQUENCY (MHz)
MAX8884Y/Z toc29
VIN = 4.2V
SWITCHING FREQUENCY (MHz)
0V
100µs/div
2.4
SWITCHING FREQUENCY (MHz)
MAX8884Y/MAX8884Z
700mA DC-DC Step-Down Converters
with Dual 300mA LDO in 2mm x 2mm CSP
900
100
300
500
700
LOAD CURRENT (mA)
_______________________________________________________________________________________
900
700mA DC-DC Step-Down Converters
with Dual 300mA LDO in 2mm x 2mm CSP
PIN
NAME
FUNCTION
Reference Noise Bypass. Bypass REFBP to AGND with a 0.033µF ceramic capacitor to reduce noise
on the LDO outputs. REFBP is internally pulled to ground through a 1kΩ resistor during shutdown.
A1
REFBP
A2
AGND
A3
NC1
A4
PGND
Power Ground for Step-Down Converter. Connect to common ground plane.
B1
LDO2
300mA LDO Regulator 2 Output. For 300mA application, bypass LDO2 with a 2.2µF ceramic capacitor
as close as possible to LDO2 and AGND. For low-output current capability, up to 10mA, an output
capacitor of 0.1µF is sufficient to keep the output voltage stable. LDO2 is internally pulled to ground
through a 100Ω resistor when this regulator is disabled.
B2
BUCK_EN
Step-Down Converter Enable Input. Connect BUCK_EN to IN1_ or logic-high for normal operation.
Connect BUCK_EN to AGND or logic-low for step-down shutdown mode.
B3
LDO2_EN
LDO2 Enable Input. Connect LDO2_EN to IN2 or logic-high for normal operation. Connect LDO2_EN to
AGND or logic-low for LDO2 shutdown mode.
B4
LX
Inductor Connection. Connect an inductor from LX to the output of the step-down converter.
C1
IN2
Supply Voltage Input for LDO1, LDO2, and Internal Reference. Connect IN2 to a battery or supply
voltage from 2.7V to 5.5V. Bypass IN2 with a 4.7µF ceramic capacitor as close as possible to IN2 and
AGND. Connect IN2 to the same source as IN1A and IN1B.
C2
SEL
Output Voltage Selection for LDO1 and Step-Down Converter. Connect to IN1_ or AGND for output
voltage selection. See Table 1.
Low-Noise Analog Ground. Connect to common ground plane.
No Internal Connection. Connect NC1 to ground.
IN1B, IN1A
Supply Voltage Input for Step-Down Converter. Connect IN1B and IN1A to a battery or supply voltage
from 2.7V to 5.5V. Bypass the connection of IN1B and IN1A with a 2.2µF ceramic capacitor as close as
possible to IN1B, IN1A, and PGND. IN1A and IN1B are internally connected together. Connect IN1A
and IN1B to the same source as IN2.
D1
LDO1
300mA LDO Regulator 1 Output. For 300mA application, bypass LDO1 with a 2.2µF ceramic capacitor
as close as possible to LDO1 and AGND. For low-output current capability, up to 10mA, an output
capacitor of 0.1µF is sufficient to keep output voltage stable. LDO1 is internally pulled to AGND
through a 100Ω resistor when this regulator is disabled.
D2
LDO1_EN
LDO1 Enable Input. Connect LDO1_EN to IN2 or logic-high for normal operation. Connect LDO1_EN to
AGND or logic-low for LDO1 shutdown mode.
D3
NC2
D4
FB
C3, C4
No Internal Connection. Connect NC2 to ground.
FB is Connected to the Internal Feedback Network
Detailed Description
The MAX8884Y/MAX8884Z are designed to power the
subcircuits within a system. These ICs contain a highfrequency, high-efficiency step-down converter and two
LDOs. The step-down converter delivers 700mA with
either 1.2V or 1.8V selectable output voltage using SEL.
The hysteretic PWM control scheme provides extremely
fast transient response, while 2MHz and 4MHz switching frequency options allow the trade-off between efficiency and the smallest external components. The
MAX8884Y/MAX8884Z linear regulators can be used to
power loads requiring a low output noise supply.
Step-Down Converter Control Scheme
A hysteretic PWM control scheme ensures high efficiency, fast switching, fast transient response, low-output
voltage ripple, and physically tiny external components.
The control scheme is simple: when the output voltage
is below the regulation threshold, the error comparator
begins a switching cycle by turning on the high-side
switch. This high-side switch remains on until the minimum on-time expires and output voltage is within regulation, or the inductor current is above the current-limit
threshold. Once off, the high-side switch remains off
until the minimum off-time expires and the output voltage falls again below the regulation threshold. During
_______________________________________________________________________________________
9
MAX8884Y/MAX8884Z
Pin Description
MAX8884Y/MAX8884Z
700mA DC-DC Step-Down Converters
with Dual 300mA LDO in 2mm x 2mm CSP
the off period, the low-side synchronous rectifier turns
on and remains on until the high-side switch turns on
again. The internal synchronous rectifier eliminates the
need for an external Schottky diode.
Hysteretic control is sometimes referred to as ripple control, since voltage ripple is used to control when the highside and low-side switches are turned on and off. To
ensure stability with low ESR ceramic output capacitors,
the MAX8884Y/MAX8884Z combine ripple from the output with the ramp signal generated by the switching
node (LX). This is seen in Figure 2 with resistor R1 and
capacitor C1 providing the combined ripple signal.
Injecting ramp from the switch node also improves line
regulation, since the slope of the ramp adjusts with
changes in input voltage.
Hysteretic control has a significant advantage over fixed
frequency control schemes: fast transient response.
Hysteretic control uses an error comparator, instead of
an error amplifier with compensation, and there is no
fixed frequency clock. Therefore, a hysteretic converter
reacts virtually immediately to any load transient on the
output, without having to wait for a new clock pulse, or
for the output of the error amplifier to move, as with a
fixed-frequency converter.
With a fixed-frequency step-down converter, the magnitude of output voltage ripple is a function of the switching
frequency, inductor value, output capacitor and ESR,
and input and output voltage. Since the inductance value
and switching frequency are fixed, the output ripple
varies with changes in line voltage. With a hysteretic
step-down converter, since the ripple voltage is essentially fixed, the switching frequency varies with changes
in line voltage. Some variation with load current is also
seen, however, this is part of what gives the hysteretic
converter its great transient response.
See the Typical Operating Characteristics section for
more information on how switching frequency can
change with load and line changes.
At inductor currents below 40mA (60mA), the MAX8884Y
(MAX8884Z) automatically switches to pulse-skipping
mode to improve light-load efficiency. Output voltage
ripple remains low at all loads, while the skip-mode
switching frequency remains ultrasonic down to 1mA
(typ) loads.
Voltage Positioning Load Regulation
The MAX8884Y/MAX8884Z step-down converters utilize
a unique feedback network. By taking a DC feedback
from the LX node through R1 in the Block Diagram, the
usual phase lag due to the output capacitor is
10
removed, making the loop exceedingly stable and
allowing the use of very small ceramic output capacitors. To improve the load regulation, resistor R3 is
included in the feedback (see the Block Diagram). This
configuration yields load regulation equal to half the
inductor’s series resistance multiplied by the load current. This voltage positioning load regulation greatly
reduces overshoot during load transients.
I
× RDCR
VBUCK = VBUCK _ NO _ LOAD − LOAD
2
ILOAD = load current
RDCR = DC impedance of inductor
VBUCK _ NO _ LOAD = 1.2V or 1.8V depending on SEL
SEL Output Voltage Selection
SEL is used to determine the output voltage of the buck
converter and LDO1. See Table 1.
Shutdown Mode
Drive BUCK_EN to logic-low to place the MAX8884Y/
MAX8884Z step-down converter in shutdown mode. In
shutdown, the control circuitry, internal switching
MOSFET, and synchronous rectifier turn off and LX
becomes high impedance.
The LDOs are individually enabled. Connect LDO1_EN
and LDO2_EN to GND or logic-low to place LDO1 and
LDO2 in shutdown mode. In shutdown, the outputs of
the LDOs are pulled to ground through an internal
100Ω resistor.
When the step-down converter and all LDOs are in shutdown, the MAX8884Y/MAX8884Z enter a very low-power
state, where the input current drops to 0.1µA (typ).
Step-Down Converter Soft-Start
The MAX8884Y/MAX8884Z step-down converter uses
internal soft-start circuitry to limit inrush current at startup,
reducing transients on the input source. Soft-start is particularly useful for supplies with high output impedance such
as Li+ and alkaline cells. See the soft-start waveforms in
the Typical Operating Characteristics.
Table 1. SEL Output Voltage Selection
SEL
BUCK CONVERTER
OUTPUT VOLTAGE
(V)
LDO1
OUTPUT VOLTAGE
(V)
AGND
1.2
1.8
IN1_
1.8
2.8
______________________________________________________________________________________
700mA DC-DC Step-Down Converters
with Dual 300mA LDO in 2mm x 2mm CSP
Applications Information
Output Voltages
The MAX8884Y/MAX8884Z DC-DC step-down converter sets the BUCK and LDO1 output voltage based on
the state of SEL. See Table 1.
Contact the factory for other output voltage options.
LDO Dropout Voltage
The regulator’s minimum input/output differential (or
dropout voltage) determines the lowest usable supply
voltage. In battery-powered systems, this determines the
useful end-of-life battery voltage. Because the
MAX8884Y/MAX8884Z LDOs use a p-channel MOSFET
pass transistor, their dropout voltages are a function of
drain-to-source on-resistance (RDS(ON)) multiplied by the
load current (see the Typical Operating Characteristics).
tors with X5R or X7R dielectric are highly recommended
due to their small size, low ESR, and small temperature
coefficients. Due to the unique feedback network, the output capacitance can be very low. A 2.2µF ceramic capacitor is recommended for most applications. For optimum
load-transient performance and very low output ripple, the
output capacitor value can be increased.
For LDO1 and LDO2, the minimum output capacitance
required is dependent on the load currents. For loads
lighter than 10mA, it is sufficient to use a 0.1µF ceramic
capacitor for stable operation over the full temperature
range. For loads up to 200mA, an output capacitor of
1µF is sufficient for stable operation over the entire temperature range. Operating the LDO at maximum rated
current the LDO1 and LDO2 requires a 2.2µF ceramic
capacitor. Using larger output capacitors reduces output noise and improves load-transient response, stability, and power-supply rejection.
Note that some ceramic dielectrics exhibit large capacitance and ESR variation with temperature. With dielectrics
such as Z5U and Y5V, it is necessary to use 4.7µF or more
to ensure stability at temperatures below -10°C. With X7R
or X5R dielectrics, 2.2µF is sufficient at all operating temperatures. These regulators are optimized for ceramic
capacitors. Tantalum capacitors are not recommended.
Inductor Selection
Input Capacitor Selection
The MAX8884Y operates with a switching frequency of
2MHz and utilizes a 2.2µH inductor. The MAX8884Z
operates with a switching frequency of 4MHz and utilizes a 1µH inductor. The higher switching frequency of
the MAX8884Z allows the use of physically smaller
inductors at the cost of lower efficiency. The lower
switching frequency of the MAX8884Y results in greater
efficiency at the cost of a physically larger inductor.
See the Typical Operating Characteristics for efficiency
graphs for both the MAX8884Y and the MAX8884Z.
The inductor’s DC current rating only needs to match the
maximum load of the application because the
MAX8884Y/MAX8884Z feature zero current overshoot
during startup and load transients. For optimum transient
response and high efficiency, choose an inductor with
DC series resistance in the 50mΩ to 150mΩ range. See
Table 2 for suggested inductors and manufacturers.
The input capacitor (CIN1) of the DC-DC step-down
converter reduces the current peaks drawn from the
battery or input power source and reduces switching
noise in the MAX8884Y/MAX8884Z. The impedance of
CIN1 at the switching frequency should be kept very
low. Ceramic capacitors with X5R or X7R dielectric are
highly recommended due to their small size, low ESR,
and small temperature coefficients. A 2.2µF ceramic
capacitor is recommended for most applications. For
optimum noise immunity and low input ripple, the input
capacitor value can be increased.
For the LDOs, use an input capacitance equal to the
value of the sum of the output capacitance of LDO1 and
LDO2. Larger input capacitor values and lower ESR provide better noise rejection and line transient response.
Note that some ceramic dielectrics exhibit large capacitance and ESR variation with temperature. With dielectrics
such as Z5U and Y5V, it may be necessary to use two
times the sum of the output capacitor value of LDO1 and
LDO2 (or larger) to ensure stability at temperatures below
-10°C. With X7R or X5R dielectrics, a capacitance equal
to the sum is sufficient at all operating temperatures.
Output Capacitor Selection
For the DC-DC step-down converter, the output capacitor
CBUCK is required to keep the output voltage ripple small
and ensure regulation loop stability. CBUCK must have low
impedance at the switching frequency. Ceramic capaci-
______________________________________________________________________________________
11
MAX8884Y/MAX8884Z
Thermal Shutdown
Thermal shutdown limits total power dissipation in the
MAX8884Y/MAX8884Z. If the junction temperature
exceeds +160°C, thermal shutdown circuitry turns off
the MAX8884Y/MAX8884Z, allowing the ICs to cool.
The ICs turn on and begin soft-start after the junction
temperature cools by 20°C. This results in a pulsed output during continuous thermal-overload conditions.
MAX8884Y/MAX8884Z
700mA DC-DC Step-Down Converters
with Dual 300mA LDO in 2mm x 2mm CSP
Table 2. Suggested Inductors
MANUFACTURER
SERIES
INDUCTANCE
(µH)
ESR
()
CURRENT RATING
(mA)
DIMENSIONS
(mm)
CB2016T
1.0
2.2
0.09
0.13
510
2.0 x 1.6 x 1.8
= 5.8mm3
CB2518T
2.2
4.7
0.09
0.13
510
340
2.5 x 1.8 x 2.0 = 9mm3
MIPF2520
1.0
1.5
2.2
0.05
0.07
0.08
1500
1500
1300
2.5 x 2.0 x 1.0
= 5mm3
MIPF2016
1.0
2.2
0.11
1100
2.0 x 1.6 x 1.0
= 3.2mm3
LQH32C_53
1.0
2.2
0.06
0.10
1000
790
3.2 x 2.5 x 1.7
= 14mm3
D3010FB
1.0
0.20
1170
3.0 x 3.0 x 1.0
= 9mm3
D2812C
1.2
2.2
0.09
0.15
860
640
3.0 x 3.0 x 1.2
= 11mm3
D310F
1.5
2.2
0.13
0.17
1230
1080
3.6 x 3.6 x 1.0
= 13mm3
D312C
1.5
2.2
0.10
0.12
1290
1140
3.6 x 3.6 x 1.2
= 16mm3
CDRH2D09
1.2
1.5
2.2
0.08
0.09
0.12
590
520
440
3.0 x 3.0 x 1.0
= 9mm3
CDRH2D11
1.5
2.2
3.3
0.05
0.08
0.10
680
580
450
3.2 x 3.2 x 1.2
= 12mm3
LPO3310
1.0
1.5
2.2
0.07
0.10
0.13
1600
1400
1100
3.3 x 3.3 x 1.0
= 11mm3
ELC3FN
1.0
2.2
0.08
0.12
1400
1000
3.2 x 3.2 x 1.2
= 12mm3
ELL3GM
1.0
2.2
0.07
0.10
1400
1100
3.2 x 3.2 x 1.5
= 15mm3
KSLI-252010
1.5
2.2
0.070
0.100
2200
1800
2.5 x 2.0 x 1.0
= 5mm3
Taiyo Yuden
FDK
Murata
TOKO
Sumida
Coilcraft
Panasonic
Hitachi
12
______________________________________________________________________________________
700mA DC-DC Step-Down Converters
with Dual 300mA LDO in 2mm x 2mm CSP
The REFBP capacitor reduces the output noise of LDO1
and LDO2. A value of 0.033µF is sufficient for most applications. This value can be increased up to 0.150µF with
some effect on the soft-start time of the LDOs. See the
Typical Operating Characteristics for more information.
Do not use values greater than 0.150µF as this degrades
the performance of the internal reference voltage and has
a corresponding impact on all output voltages.
Ceramic capacitors with X5R or X7R dielectric are highly recommended due to their small size, low ESR, and
small temperature coefficients. Note that some ceramic
dielectrics exhibit large capacitance and ESR variation
with temperature. With dielectrics such as Z5U and
Y5V, it may be necessary to use two times the recommended value to achieve desired output noise performance at temperatures below -10°C. Tantalum
capacitors are not recommended.
Thermal Considerations
In most applications, the MAX8884Y/MAX8884Z do not
dissipate much heat due to their high efficiency. But in
applications where the MAX8884Y/MAX8884Z run at high
ambient temperature with heavy loads, the heat dissipated may exceed the maximum junction temperature of the
part. If the junction temperature reaches approximately
+160°C, all power switches are turned off and LX and FB
become high impedance, and LDO1 and LDO2 are
pulled down to ground through an internal 100Ω resistor.
The MAX8884Y/MAX8884Z maximum power dissipation
depends on the thermal resistance of the IC package
and circuit board, the temperature difference between
the die junction and ambient air, and the rate of airflow.
The power dissipated in the device, PDISS, is:
⎛
⎞
1
PDISS = PBUCK ⎜
− 1⎟ + ILDO1(VIN2 − VLDO1) + ILDO2 (VIN2 − VLDO2 )
⎝ ηBUCK ⎠
where ηBUCK is the efficiency of the DC-DC step-down
converter, and PBUCK is the output power of the DC-DC
step-down converter.
The maximum allowed power dissipation, PMAX, is:
PMAX =
(TJ _ MAX − TA )
θJA
where (T JMAX - T A ) is the temperature difference
between the MAX8884Y/MAX8884Z die junction and
the surrounding air, and θJA is the thermal resistance of
the junction through the PCB, copper traces, and other
materials to the surrounding air.
PCB Layout
High switching frequencies and relatively large peak
currents make the PCB layout a very important part of
design. Good design minimizes excessive EMI on the
feedback paths and voltage gradients in the ground
plane, resulting in a stable and well regulated output.
Minimize the ground loop formed by CIN1, CBUCK, and
PGND. To do this, connect CIN1 close to IN1A/IN1B
and PGND. Connect the inductor and output capacitor
as close as possible to the IC and keep their traces
short, direct, and wide. Keep noisy traces, such as the
LX node, as short as possible. Connect AGND and
PGND to the common ground plane. Figure 1 illustrates
an example PCB layout and routing scheme.
______________________________________________________________________________________
13
MAX8884Y/MAX8884Z
Reference Noise
Bypass Capacitor Selection
SEL
LDO2_EN
BUCK_EN
LDO1_EN
MAX8884Y/MAX8884Z
700mA DC-DC Step-Down Converters
with Dual 300mA LDO in 2mm x 2mm CSP
GND
CREFBP
LDO2
REFBP
AGND
NC1
PGND
A1
A2
A3
A4
BUCK_EN LDO2_EN
LDO2
LX
B1
B2
B3
B4
IN2
SEL
IN1B
IN1A
C1
C2
C3
C4
LDO1
LDO1_EN
NC2
FB
D1
D2
D3
D4
CIN1
CLDO2
CBUCK
3.8mm
CIN2
CLDO1
LBUCK
IN
BUCK
LDO1
4.0mm
Figure 1. Recommended PCB Layout
14
______________________________________________________________________________________
700mA DC-DC Step-Down Converters
with Dual 300mA LDO in 2mm x 2mm CSP
IN1A
IN1B
REF
PWM
ERROR AMP
R7
PWM LOGIC
SEL
R6
LX
C2
STEP-DOWN
CURRENT LIMIT
PGND
FB
R1
C1
R3
R2
IN2
REFBP
REFBP
CURRENT LIMIT
REF
AGND
ERROR
AMP
LDO1
R9
LDO1_EN
LDO2_EN
SEL
BUCK_EN
CONTROL
LOGIC
R8
LDO1_EN
SEL
R7
REFBP
CURRENT LIMIT
ERROR
AMP
MAX8884Y
MAX8884Z
LDO2
R12
LDO2_EN
R11
R10
______________________________________________________________________________________
15
MAX8884Y/MAX8884Z
Block Diagram
700mA DC-DC Step-Down Converters
with Dual 300mA LDO in 2mm x 2mm CSP
MAX8884Y/MAX8884Z
Typical Application Circuit
IN1A
Li+
BATTERY
2.2µF
MAX8884Y
MAX8884Z
IN1B
2–4MHz
BUCK
BASEBAND
PROCESSOR
2.2µH (MAX8884Y)
1.0µH (MAX8884Z)
LX
FB
1.2V
CAMERA MODULE
CORE
2.2µF
BUCK_EN
LDO1_EN
LDO2_EN
SEL
GPIO
GPIO
GPIO
PGND
CONTROL
REFBP
4.7µF
IN2
REF
AGND
0.033µF
LDO1
DIGITAL
2.2µF
LDO1
LDO2
ANALOG
2.2µF
LDO2
Package Information
For the latest package outline information and land patterns, go to www.maxim-ic.com/packages. Note that a “+”, “#”, or “-” in the
package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing pertains to the
package regardless of RoHS status.
16
PACKAGE TYPE
PACKAGE CODE
DOCUMENT NO.
16 CSP
R162A2+1
21-0226
______________________________________________________________________________________
700mA DC-DC Step-Down Converters
with Dual 300mA LDO in 2mm x 2mm CSP
REVISION
NUMBER
REVISION
DATE
0
4/09
Initial release
1
1/10
Added switching frequency TOCs and updated Step-Down Converter Control
Scheme section
DESCRIPTION
PAGES
CHANGED
—
8, 10
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 ____________________ 17
© 2010 Maxim Integrated Products
Maxim is a registered trademark of Maxim Integrated Products, Inc.
MAX8884Y/MAX8884Z
Revision History